JP4438672B2 - Backlight and display device - Google Patents

Description

  The present invention relates to a backlight suitable for application to, for example, a liquid crystal display device and a display device including the backlight.

  In the liquid crystal display device, since the pixels arranged on the display panel do not emit light, a backlight is arranged on the back of the display panel, and the back is illuminated with the backlight to display an image or the like. . The display area of the display panel is increasing, and the backlight itself is becoming very large.

  FIG. 8 is a diagram illustrating a configuration example of a backlight disposed on the back surface of a display panel of a conventional liquid crystal display device. FIG. 8A is a view seen from the front, and FIG. 8B is a cross-sectional view seen from the side. In this example, a cold cathode fluorescent lamp (CCFL) is used as a light emitting member, and a plurality of cold cathode fluorescent lamps 2 arranged horizontally in the light box 1 constituting the backlight are vertically arranged. It is arranged. A reflective member 3 is disposed on the back of the fluorescent lamp 2. The scattering plate 4 is disposed on the front surface of the light box 1 in which each cold cathode fluorescent lamp 2 is disposed (here, the side on which the display panel is disposed will be described as the front and the opposite side will be described as the back. The same applies hereinafter). It is. The scattering plate 4 is substantially the same size as the display area of the display panel, and is made of, for example, an acrylic plate having a predetermined thickness so as to scatter light. Further, a plurality of scattering sheets 5 and 6 are arranged on the front surface of the scattering plate 4. Each of the scattering sheets 5 and 6 is formed of a thin film resin and has a property of giving a certain degree of directivity to light, for example.

  When an image is displayed on a liquid crystal display device using a backlight having such a configuration, backlight emission control, called blinking, may be performed in order to improve moving image response. That is, the liquid crystal display panel temporarily becomes in a state where the display state is not fixed during the period in which the display signal is written to the pixels arranged in the panel, and when such a state is seen, The image quality, particularly the responsiveness of the moving image, is deteriorated. For this reason, during the period when the display signal is written to each pixel, the backlight on the back of the corresponding line (horizontal line) is turned off to improve the response of the moving image.

  In order to perform this blinking, for example, in the case of the structure of FIG. 8, if the signal writing to the pixel is performed sequentially from the horizontal line on one screen in one field period, the horizontal writing is performed. The cold cathode fluorescent lamps 2 located on the back of the line are temporarily turned off sequentially from the top. FIG. 9 is a diagram showing an example of the brightness state of the entire display screen when the specific cold cathode fluorescent lamp 2 is turned off in this way. In the example of FIG. 9, the timing at which the cold cathode fluorescent lamp at the center is turned off is shown.

  As shown in FIG. 9, even if there is a place where the lamp is turned off, the adjacent lamp is turned on, so the contrast of light and dark is not sufficient between the place where the lamp is turned off and the other places. There was a problem that the brightness of the portion was not sufficiently lowered and the blinking effect was not sufficient.

  In order to solve this problem, for example, a backlight having the structure shown in FIG. 10 has been proposed. FIG. 10A is a view seen from the front, and FIG. 10B is a cross-sectional view seen from the side. In this example, a partition member 3a is provided on the reflecting member 3 'disposed on the back surface of the fluorescent lamp 2, and the fluorescent lamp 2 is disposed in different spaces partitioned by the partition member 3a. . A scattering plate 4 is disposed on the front surface of the partition member 3a, and a plurality of scattering sheets 5 and 6 are disposed on the front surface thereof.

  In this way, by arranging the partition member so that the light from each fluorescent lamp does not interfere with each other, as shown in FIG. 9, the contrast of light and dark between the light-off portion and the other portions as shown in FIG. Can solve problems that are not sufficient.

Patent Document 1 discloses a backlight having a structure in which a partition member is provided as described above.
JP 2002-72167 A (FIGS. 5 and 6)

  However, in the case of a backlight having a structure in which a conventional partition plate is provided, there is a problem in that streak unevenness occurs on the display screen. FIG. 10 is a diagram showing an example of the occurrence of the stripe unevenness, and there is a problem that the stripe unevenness in which the brightness of the backlight at the position where the partition member is provided slightly decreases occurs. In order to solve this problem, for example, it is conceivable that the degree of light scattering by the scattering plate is increased to eliminate streaks, but if this is done, the brightness of the backlight decreases. As a result, the backlight becomes inefficient. In addition, Patent Document 1 described above also describes a structure in which the thickness of the scattering plate is reduced to make streak unevenness as inconspicuous as possible, but this is not a sufficient solution.

  When the backlight having the configuration shown in FIG. 10 is actually manufactured and the display device is assembled, it is ideal to eliminate the gap between the tip of the partition member 3a and the scattering plate 4, but in practice, Due to the dimensional accuracy of each member, it was difficult to completely eliminate the gap. In particular, in recent years, display devices that require this type of backlight tend to be large (for example, the diagonal length of the screen is 40 inches or more), and the structure shown in FIG. It was difficult.

  The present invention has been made in view of such a point, and an object thereof is to eliminate display unevenness when performing blinking.

  A first invention provides a plurality of light sources arranged in parallel as a backlight, individually transmits light from the plurality of light sources to the display unit side, and a partition portion having a thin tip, and a partition The scattering sheet is bonded to the thin-walled portion at the tip of the part, and the scattering plate having a predetermined thickness is disposed on the front surface of the scattering sheet.

  By doing in this way, the member which touches the front-end | tip of a partition part is a scattering sheet | seat which is a sheet-like member which has a certain amount of flexibility, and it is easy to make it adhere | attach in the state which the front-end | tip of a partition part and the scattering sheet contact | adhered It is possible to effectively prevent the occurrence of streaks.

  According to a second aspect of the present invention, a plurality of light sources arranged in parallel is prepared as a backlight, and light from the plurality of light sources is individually transmitted to the display unit side, and a partition portion having a thin tip is provided, and a display The curved scattering plate and the surface of the curved scattering plate are brought into contact with the tip of the partition portion in the direction in which a plurality of light sources are arranged in a shape corresponding to the display area of the portion and having a predetermined thickness. In this state, one end and the other end of the scattering plate are provided with a connection member that connects to the partition portion.

  By doing so, the scattering plate is fixed to the partition member by the connecting member in a state in which a force is applied in the direction opposite to the previously applied bending direction, and the tip of the partition portion and the scattering plate are in close contact with each other Thus, the occurrence of unevenness in the lines can be effectively prevented.

  According to the present invention, the leading end of the partition portion and the scattering sheet or the scattering plate are in close contact with each other, so that no gap is generated between the leading end of the partition portion, so that the occurrence of so-called streak unevenness is prevented, Light from the light emitting unit can be transmitted individually. For example, when a blinking process for temporarily turning off some of the light emitting units is performed, the contrast between the off unit and the lighting unit is sufficiently good. . Therefore, a display device provided with this backlight can perform a good display with excellent moving image response.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  In this example, the present invention is applied to a liquid crystal display device. First, a configuration example of the entire liquid crystal display device will be described with reference to FIG. The video signal input to the display device of this example is supplied to the liquid crystal panel control circuit 11, and a signal for performing display driving on the liquid crystal display panel 12 is generated based on the video signal. The generated display drive signal is supplied to the source driver 13 and the gate driver 14 of the liquid crystal display panel 12, and the display signal is written to each pixel on the panel. The writing of the display signal is performed, for example, in one field cycle in synchronization with the field cycle of the supplied video signal.

  A backlight is disposed on the back surface of the liquid crystal display panel 12. In this example, as a light source constituting the backlight, a light source 21 in which a plurality of light emitting diodes are arranged in series in the horizontal direction is arranged in the vertical direction. As the plurality of light emitting diodes, for example, a red light emitting diode, a green light emitting diode, and a blue light emitting diode are arranged in a predetermined state so as to be white.

  The light source 21 is controlled by the light source control circuit 15. The light source control circuit 15 is supplied with a vertical synchronization signal of the video signal from the liquid crystal panel control circuit 11 and performs a process of temporarily turning off a plurality of prepared light sources 21 in order in synchronization with the vertical period. The position where the light source 21 is turned off coincides with the position of the horizontal line where writing to the pixels of the liquid crystal display panel 12 arranged before the turned-off position is performed. King processing is performed.

  Next, the configuration of the backlight of this example will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a backlight cut in the vertical direction. As shown in FIG. 1, a plurality of prepared light sources 21 are arranged in the vertical direction, and a reflecting member 30 having a partition portion 31 is arranged on the back side of each light source 21. The partition portion 31 has a thin tip and is continuously formed in the same shape in the horizontal direction. In the example of FIG. 1, the reflecting member 30 on the back surface of the light source 21 has a semicircular shape, but may have a linear shape as shown in FIG. 3 described later.

  The surface of the reflecting member 30 is subjected to a surface treatment including a partition portion 31 with a high light reflectance. However, in the case of this example, the reflectance of the light is slightly reduced at the front end side of the partition portion 31, and the reflectance is increased between the rear end side of the partition portion 31 and the surface of the remaining reflecting member 30. It is.

  That is, for example, as shown in FIG. 3, as the front end portion 31 a of the partition portion 31, the light reflectance is relatively low, and the rear end portion 31 b of the partition portion 31 and the bottom portion 32 of the reflection member 30 are The light reflectance is relatively high. As a process for changing the reflectance in this way, for example, the reflecting member 30 including the partition portion 31 is formed of white resin, and the tip portion 31a of the partition portion 31 exposes the resin as it is on the surface. Then, the rear end portion 31b and the bottom portion 32 of the partition portion 31 are painted with a white paint containing particles suitable for reflection such as barium carbonate. In the example of FIG. 3, the bottom portion 32 has a linear shape, but may have a semicircular shape as shown in FIG. These shapes may be selected according to the characteristics of the light source to be used.

  Returning to the description of FIG. 1, the scattering sheet 45 is disposed at the tip 31 a of the partition 31 configured as described above. The scattering sheet 45 is made of, for example, a thin resin sheet having a thickness of 1 mm or less, and has a function of giving directionality to light. This scattering sheet 45 is made to adhere to the tip part 31 a of the partition part 31. As this adhesion treatment, for example, an adhesive (or a pressure-sensitive adhesive) is uniformly applied in advance to the back side of the scattering sheet, and when disposing on the partition portion 31, the scattering sheet 45 is lightly pressed to separate the partition portion. Adhesion is performed in such a state that the gap between the tip of 31 and the scattering sheet 45 is completely eliminated. Adhesion without such a gap is possible because the scattering sheet 45 is a thin film and is a material having a certain degree of flexibility.

  Then, as shown in FIG. 1, a scattering plate 42 having a certain thickness (for example, about several millimeters in thickness) is arranged on the front side of the scattering sheet 45 to scatter light from the light source. Further, two scattering sheets 43 and 44 are arranged on the front surface of the scattering plate 42.

  Although not shown in FIG. 1, the liquid crystal display panel 12 shown in FIG. 2 is arranged on the front side of the scattering sheet 44, and the entire image display surface of the liquid crystal display panel 12 is illuminated from the back side. Accordingly, the reflecting member 30, the scattering plate 42, and the scattering sheets 43, 44, and 45 are sized corresponding to the display area of the liquid crystal display panel 12.

  The scattering sheets 43 and 44 and the scattering plate 42 are arranged with a slight gap from the adjacent scattering plates or sheets.

  According to the display device having the backlight of the present example configured as described above, the backlight is in a good light emitting state with no stripe unevenness. That is, as a configuration in which the partition portion 31 is provided, the light from each light source 21 is individually delivered, but since the tip of the partition portion 31 and the scattering sheet 45 are in close contact with each other, FIG. As shown in FIG. 4, the light emission state is obtained in which no stripe unevenness occurs. And since the light from each light source is completely partitioned, when a blinking process is performed and a part of the light sources is turned off, for example, as shown in FIG. The contrast with the part is high, and the light-off point is sufficiently dark.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6, the same reference numerals are given to the portions corresponding to FIGS. 1 to 4 described in the first embodiment.

  This example is also applied to the liquid crystal display device, and the configuration of the entire display device is the same as the configuration described with reference to FIG. 2, and the description thereof is omitted here. FIG. 5 is a cross-sectional view showing the backlight provided in the display device of this example cut in the vertical direction. As shown in 51, a plurality of prepared light sources 21 are arranged in the vertical direction, and a reflecting member 30 having a partition portion 31 is arranged on the back side of each light source 21. The partition portion 31 has a thin tip and is continuously formed in the same shape in the horizontal direction.

  The reflecting member 30 itself is the same as the reflecting member 30 described in the first embodiment. That is, as shown in FIG. 3 which has already been described, the light reflectance is relatively low as the tip portion 31 a of the partition portion 31, and the rear end portion 31 b of the partition portion 31 and the bottom portion 32 of the reflection member 30. The light reflectance is relatively high.

  And in this example, as shown in FIG. 5, the scattering plate 42 is arrange | positioned at the front-end | tip part 31a of the partition part 31 comprised in this way. The scattering plate 42 of this example is configured by, for example, filling an acrylic plate having a thickness of several mm with a material having a scattering action. As shown in FIG. 6 to be described later, the scattering plate 42 of this example has a shape that is slightly curved in the vertical direction, and is applied with a certain amount of pressure so that the upper and lower sides are sandwiched between the connecting members 51 and 52, and the reflecting member 30. The scattering plate 42 is connected in close contact.

  That is, when the assembled state is shown in FIG. 6, in the state before the assembly, as shown in FIG. 6A, the scattering plate 42 is bent and only the central part is in contact with the tip part 31 a of the partition part 31. Is connected to the reflecting member 30 to which the partition portion 31 is attached by being sandwiched between the connecting members 51 and 52 from above and below, and assembled in the state shown in FIG. By assembling in this way, the force sandwiched between the connecting members 51 and 52 is applied, and the tip portions 31a of all the partition portions 31 are in complete contact with the back surface of the scattering plate.

  Returning to the description of FIG. 5, the two scattering sheets 43 and 44 are arranged on the front side of the scattering plate 42 assembled in this way. The scattering sheets 43 and 44 are thin film sheets having a thickness of, for example, 1 mm or less, and have effects such as adjusting the direction of light.

  Although not shown in FIG. 5, the liquid crystal display panel 12 shown in FIG. 2 is arranged on the front side of the scattering sheet 44, and the entire image display surface of the liquid crystal display panel 12 is illuminated from the back side. Therefore, also in this example, the reflecting member 30, the scattering plate 42, and the scattering sheets 43 and 44 have a size corresponding to the display area of the liquid crystal display panel 12.

  The scattering sheets 43 and 44 and the scattering plate 42 are arranged with a slight gap from the adjacent scattering plates or sheets.

  With this configuration, a good light emission state without streak unevenness is obtained. That is, as a configuration in which the partition portion 31 is provided, the light from each light source 21 is individually delivered. However, since the tip of the partition portion 31 and the scattering plate 42 are in close contact with each other, FIG. As shown in FIG. 4, the light emission state is obtained in which no stripe unevenness occurs. And since the light from each light source is completely partitioned, when the blinking process is performed and some of the light sources are turned off, the contrast between the turned off part and the turned on part is high, and the light is turned off. Is sufficiently dark.

  In the example of FIG. 5, the scattering sheets 43 and 44 on the front side are not fixed by the connecting member, but the scattering sheets 43 and 44 may also be fixed by the connecting member. That is, for example, as shown in FIG. 7, the scattering sheets 43 and 44 may be included and fixed between the connection members 51 ′ and 52 ′. In this case, when a certain amount of gap is required between the scattering sheets 43 and 44 and the scattering plate 42, some spacers are arranged vertically between the members 42, 43 and 44, and the connecting member 51. What is necessary is just to make it pinch | interpose with ', 52'.

  In the embodiment described so far, an example in which light emitting diodes are arranged and used as a light source provided in the backlight is used, but other light emitting means such as a cold cathode fluorescent lamp may be used. However, when performing the blinking process, it is preferable to use a light emitting and extinguished response, and the light emitting diode is excellent in terms of characteristics.

It is sectional drawing which shows the structural example by the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the display apparatus by the 1st Embodiment of this invention. It is a perspective view which shows the example of the partition plate by the 1st Embodiment of this invention. It is explanatory drawing which shows the example of the blinking state by the 1st Embodiment of this invention. It is sectional drawing which shows the structural example by the 2nd Embodiment of this invention. It is explanatory drawing which shows the example of the assembly state by the 2nd Embodiment of this invention. It is sectional drawing which shows the modification of the structure by the 2nd Embodiment of this invention. It is explanatory drawing which shows the structural example of the conventional liquid crystal display device. It is explanatory drawing which shows the example of the conventional light emission state. It is explanatory drawing which shows the structural example of the conventional liquid crystal display device. It is explanatory drawing which shows the example of the conventional light emission state.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Liquid crystal display panel, 15 ... Light source control circuit, 21 ... Light source, 30 ... Reflective member, 31 ... Partition part, 31a ... Tip part, 31b ... Rear end part, 32 ... Bottom part, 41 ... Light box, 42 ... Scattering plate , 43, 44, 45 ... scattering sheets, 51, 51 ', 52, 52' ... connecting members

Claims (6)

In the backlight that illuminates the back of the display unit,
Corresponding to the display area of the display unit, a plurality of light sources arranged in parallel,
The light from each of the plurality of light sources is individually transmitted to the display unit side, and a partition portion having a thin tip, and
The scattering sheet is a shape corresponding to the display area of the display unit, and is bonded to the thin part at the tip of the partition part,
A backlight having a shape corresponding to a display area of the display unit, a predetermined thickness, and a scattering plate disposed in front of the scattering sheet. The backlight according to claim 1,
The said partition part changed the reflectance of light with the surface of the front end side, and the surface of back, and made the reflectance of the back surface higher than the surface of the front end side, The backlight characterized by the above-mentioned. In the backlight that illuminates the back of the display unit,
Corresponding to the display area of the display unit, a plurality of light sources arranged in parallel,
The light from each of the plurality of light sources is individually transmitted to the display unit side, and a partition portion having a thin tip, and
A scattering plate having a curved shape with respect to the direction in which a plurality of the light sources are arranged, having a predetermined thickness in a shape corresponding to the display area of the display unit,
A backlight comprising: a connecting member that connects one end and the other end of the scattering plate to the partition portion in a state where the surface of the curved scattering plate is in contact with the tip of the partition portion. The backlight according to claim 3,
The said partition part changed the reflectance of light with the surface of the front end side, and the surface of back, and made the reflectance of the back surface higher than the surface of the front end side, The backlight characterized by the above-mentioned. A display unit for displaying an image corresponding to the input image signal;
In a display device comprising a backlight that illuminates the back surface of the display unit,
As the backlight,
Corresponding to the display area of the display unit, a plurality of light sources arranged in parallel,
The light from each of the plurality of light sources is individually transmitted to the display unit side, and a partition portion having a thin tip, and
The scattering sheet is a shape corresponding to the display area of the display unit, and is bonded to the thin part at the tip of the partition part,
A display device comprising: a scattering plate having a predetermined thickness in a shape corresponding to a display area of the display unit, and disposed on a front surface of the scattering sheet. A display unit for displaying an image corresponding to the input image signal;
In a display device comprising a backlight that illuminates the back surface of the display unit,
As the backlight,
Corresponding to the display area of the display unit, a plurality of light sources arranged in parallel,
The light from each of the plurality of light sources is individually transmitted to the display unit side, and a partition portion having a thin tip, and
A scattering plate having a curved shape with respect to the direction in which a plurality of the light sources are arranged, having a predetermined thickness in a shape corresponding to the display area of the display unit,
A display device, comprising: a connecting member that connects one end and the other end of the scattering plate to the partition portion in a state where the surface of the curved scattering plate is in contact with the tip of the partition portion.